The following invention relates generally to workholders for lathes which allows a conventional three jaw chuck to turn quadrilateral stock material.
More particularly, the instant invention is directed to an instrumentality for obviating the necessity of tearing down a lathe in its entirety when one is required to turn square stock. Frequently, it is necessary to turn square stock or rectangular stock in an operation which constitutes a minor portion of a turning job. In such cases, it has been required to remove the existing three jaw chuck system, install a four jaw chuck and thereafter put the work stock in for the turning operation and center the work stock. Once this operation has been completed, of course, the original three jaw chuck must be replaced. Even a highly skilled artisan must spend perhaps 30 minutes or more for first removal and then replacement of the four jaw system, without the centering operation even considered. This provides a nettlesome problem, particularly when the turning operation is for a relative small quantity and the machine must be reconverted almost immediately thereafter.
There have been known prior art attempts in causing conventional three jaw chucks to lend themselves to utilization by square stock. The instant invention is easily distinguished over these known prior art techniques in that the effort involved in placing the workholder members according to the instant application is no more cumbersome than the effort required in placing the square stock in the jaws of the lathe. Thus, there is no discernible investment of time that is required for utilization of the instant device, particularly when contrasted with the known prior art.
Further, the instant invention is distinguished over the known prior art in that an instrumentality has been provided which allows a conventional three jaw chuck to turn quadrilateral stock which is formed preferably from first and second unitary workholder members diametrically opposed within a circumscribed area defined by the innermost faces of the three jaw chucks, each member having a somewhat V-shaped portion defining a crotch which engages respectively two sides of the quadrilateral stock. One of the members is caused to lay against two of the conventional jaws with the other member diametrically opposed therefrom. When the jaws are clamped tight, an aligned secured piece of square stock will be held without any of the wobble or precession that normally accompanies conversion from one known prior art system to another without centering.